You can also enlarge your lungs in a terrible way–through emphysema. This can occur as an effect of prolonged smoking, when the air sacs, or alveoli, in the lungs lose their elasticity. It becomes much more difficult to exhale, and the lungs become overinflated as a result, making them enlarged. Enlarged lungs are terrible in this case, causing breathing difficulty and forcing the heart to go into overdrive to pump blood through the lungs.